Sunday, August 14, 2011

Repairs: Ibanez FL9 Flanger

Since I don't get much time to play guitar these days and when I do, it's generally just guitar and amp. My FX don't get used too often, and the least often used of my FX would have to be my Ibanez FL9 Flanger. Generally I don't havemuch use for flanging effects. It's fun and all, but I prefer to use it sparingly. If I'm going to use a modulated effect, it's more likely that I'll use a phaser. Just personal preference.

Because of this, my FL9 sat in a drawer for the best part of a year. It's an old pedal (over 25 years) and the last time I went to use it, it just passed a clean tone. The pedal wasn't toally broken, the delay chip was still working as there as a bit of a flange sound when twiddling the controls. Upon opening it up, some of the jooints looked cold. So I proceeded to re-solder everything on the board. No go. It took a  while to track down the schematic (didn't end up using it), but I'd read a snippet from one forum about replacing old electrolytic caps, so i figured that i'd give it a try. I went over the board and documented everything electrolytic.

There were two caps near the middle of the board which weren't coloured blue like the rest (they were orange), so I decided to replace them first and give it a test (I'd seen a similar arrangement on a synth I'd built). My hunch was right, they were there to control the LFO rate. The LFO was working again, but the effect was very subtle. Not at all like I remembered.

Fortunately the board has three trim pots for adjusting various biases. Ignore the middle one, it's there to bias a transistor and the factory setting is just right to avoid unwanted and unpleasant clipping. The trim pot closes to the middle controls feedback and the one further away controls depth. With these two trim pots you can get the pedal to self oscillate. Particularly with the first one. It's not a sound I'd want all the time, so I've set it up to kick in at about 70% maximum on the front panel feedback knob. The mod is safe and easy to do. You won't even need to take the board out to do it. While increasing the feedback makes the flanger more prominent, it still falls short of being a true "jet" flanger. Still it is nice to have in the tool kit.

FL9 Service Manual Page 1

FL9 Service Manual Page 2 (Schematic)

FL9 Service Manual Page 3 (Trouble Shooting)

FL9 Service Manual Page 4 (PCB Layout) - LFO Caps Highlighted w/red box.


  1. Regarding the Ibanez fl9 flanger, if you encounter the unit not flanging clean sound comes out of the output even when activated (LED on)
    Just get the diode D103 (refer to circuit diagram) replaced and the unit should works. This component control the FET(Q103) which switch the effect on/off

  2. I have this exact issue, I am going to try to replace this diode, are different kinds of D103 diodes, or if it is labeled as D103 am I good? I located it on the the unit, I just don't know enough to be sure I solder the correct component on.

    Thank you! Please Help!

  3. Are there only one version of a D103 Diode? I found it on my unit, just want to be sure I buy the right component.


  4. I think there are different sizes, but as far as I know they're all the same in terms of function.

  5. Hey, thanks for posting this. The schematic is a little hard to read, are those 4.7pf film capacitors that you replaced in this repair?

    1. I think they were elecrtolytics, but its been a long time since I fixed it that I may be wrong.

  6. I'm trying to modify mine for true bypass with a Mammoth kit. Any idea which resistor I should be pulling to make the effect be always on? The Mammoth daughter board will control on/off after this.

    1. I'm not 100% sure on this, but in the bottom right of the 2nd image there is an "effect/Normal" label.
      Around there is a resistor network. The labels look like R141,R140,R139,R138.

      Report back with what you find :)

  7. Mine is completely dead the led does not light up, I did a little intervention a short while ago replacing the switch it was working perfectly before what could be wrong? Anyone can help?

    1. I had a Boss DS-1 which didn't power up and it turned out to be the power supply protection diode. It had actually split in two. The previous owner must have tried a very wrong power supply.

      Start with the power input then try to see if the FET switch is still working.


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